‘Suminagashi’ is a broad upright cultivar. Trees are vase-shaped when young, but gradually broaden with age. This is a fast-growing cultivar that typically grows to 8-10′ tall over the first ten years, eventually maturing to 15-20′ tall and 10-15′ wide. Branches may weep at the ends. Palmate leaves (to 4″ long) are deeply cut into seven (less frequently 9) elongate-ovate lobes each having toothed margins and pointed tips. Foliage emerges purple red in spring, matures to deep maroon in summer and finally turns bright red in fall. Small reddish flowers in spring are attractive on close inspection.